The present invention relates to hose for what is now generally referred to as drip type irrigation. In drip type irrigation, hose is positioned in spaced parallel rows across the growing area, either laying on the ground, buried in the ground, or suspended above the ground. Outlet openings are spaced along the lengths of hose. The purpose of the hose is to provide a continuous low rate of flow of water or water with fertilizer and/or pesticide, and it is desirable to have the hose operate for a long period of time without clogging or any substantial change in rate of flow at the various outlet openings and without requiring attention from the grower.
The drip irrigation hose typically comprises two or three parallel tubes with openings therebetween for fluid flow from the source through the tubes in series to the ground, with flow being controlled by the sizes of the tubes, the sizes of the flow passages between the tubes and of the outlet passages, and flow restrictions, if any, in the tubes. Typical drip irrigation hoses are shown in U.S. patents to Sahagun-Barragan No. 3,870,236; Boyle No. 3,467,142; Delmer No. 4,196,853; and Delmer No. 4,235,380; and the art of record in those patents.
In addition to the desirable characteristics of continuous and uniform controlled flow in drip irrigation hoses, initial cost is also a factor. Hose typically is made by extrusion or by sealing one or more strips together to produce the desired configuration. The U.S. patent to Allport No. 4,247,051 shows hose made from a single strip of plastic with longitudinal ribs added to provide the spacing for the primary and secondary tubes.
The U.S. patent to Tiedt No. 4,009,832 shows two different constructions. In one embodiment, a plurality of strips are bonded together without any provision for spacing between the strips. In another embodiment, a strip is extruded with spacers and connectors.
In U.S. patent to Leal-Diaz No. 4,047,995, a strip is folded on itself to provide the primary tube, with a portion of the strip being corrugated to provide a plurality of secondary tubes.
It is an object of the present invention to provide a new and improved drip irrigation hose which is made from a single strip of material without requiring any extrusions and without requiring any additional dividers or spacer strips or ribs and without requiring any corrugating of a portion of the strip to provide a secondary tube.
It is another object of the invention to provide such a drip irrigation hose which is suitable for high speed continuous production. A particular object is to provide such hose which can be produced with slits and flaps rather than requiring punching of holes and formation of compression type seals to achieve the desired flow characteristics.
Other objects, advantages, features and results will more fully appear in the course of the following description.